As completely expected (per Murphy's laws), the driver side window fell inside the door on my golf mk4 tonight evening, at -10 degrees outside.

I tried to open it (electric) going inside a parking, but it was frozen and would not budge. I suspect the guiding mechanism went down on the rails, while the window remained "suspended" and fell in a bit later missing the support on the rails and resting on the bottom of the door(I think, as it's not coming back up). Thank God it didn't shatter (although I can't really say if it didn't crack).

So, I started taking apart the door to try and fix it, but got stuck unscrewing two 8mm triple square bolts which were already stripped (guessing from previous similar work). The tool just can't get any grip on the screw head, leaving them, literally and figuratively, screwed.

I'm currently pondering my options for tomorrow, either for just unscrewing the screws (guess would have to be drilled and replaced) or just the whole operation (not much left to do tbh, would guess 30min work):
1. Local VW garage...would be nice, but they are closed on Saturdays!
2. Driving about 10km to a Seat garage where I've been before...but they might say no as the whole removal procedure is not the same for Seats?
3. Driving about 15km to ATU in Spreitenbach, but do they even do this kind of thing?
4. ?

Any advice is highly appreciated

Can't you call the garages you mentioned and ask if they can do it before you drive to them in this weather? Actually, I think most of them won't open on Saturdays.
Feel for you.